1. Field of the Invention
The present invention relates generally to wireless sensing devices and sensor communication devices.
2. Prior Art
In many industrial fields, it is important to continually measure and monitor environmental parameters. In agricultural industries, it is essential to monitor water content of soil and concentration of fertilizers. In chemical industries it is essential to monitor the air for possible hydrocarbon or toxic gas leaks that could lead to industrial accidents. At airports it is important to monitor the integrity of fencing surrounding the property. All of these applications can greatly benefit from a self-contained wireless data transmitter specifically designed to interface with sensors.
All of these example applications have similar requirements: that the device be low cost, easy to install, resistant to the weather, have long battery life, and can communicate large distances in order to easily cover a large area.
In the prior art, there exist three distinct classes of environmental sensors. The first class is of low-cost battery powered devices that are designed to operate around a home or building. They often take the form of wireless smoke detectors, motion detectors or weather stations. These devices are single purpose and short-range. There is no option to connect any external sensors or customize the sensor pack. Additionally, their short range design does not allow them to be used in large-scale industrial settings or large outdoor settings.
The second class of devices is the wireless sensor transmitters most similar to the device described in this document. They are designed to interface to a handful of different sensors and transmit the data back to a display terminal. Many of them also log data internally. While their range is relatively limited, they can transmit the data up to several thousand feet. These devices, however, are both large and expensive. They generally mount on poles or tripods in order to elevate the antenna. While they include batteries for nighttime operation, they heavily rely on solar cells to supply them with power. The mounting requirements and solar cell requirements add significant cost to the devices that impact their usability and installation time.
The third class of wireless sensor interface devices is a group of stand-alone sensor and communication devices that use wide area wireless communication technologies. These devices connect to a sensor and then communicate sensor readings via cell phone, pager, or satellite phone communication systems. These devices are designed for use in remote areas. These devices also required an above ground mounting and rely heavily on solar cells as a power source. While useful, these devices require that the operator pay for access to the wireless network. Cellular and satellite communication charges can add up quickly when transmitting data every few minutes. To avoid excessively high charges these devices often collect data for several hours or days and then transmit the data in a batch. The devices described herein use unlicensed band communication frequencies and do not require the operator to pay for service or licensing fees.